This proposal addresses the problem of lack of a scientific basis upon which to base a decision to provide endodontic treatment for persons with HIV disease; the literature contains only a few case reports with different outcomes. The primary hypothesis is that assessment of both cellular immunity depletion as well as residual cellular immunity function will be accurate predictors for endodontic success or failure, and that the CD4 lymphocyte count alone is an inadequate base for making such decisions. This study intends to correlate successful and failed endodontic treatment with measurable serological parameters that are related to other systemic health outcomes in HIV positive persons. 175 HIV positive patients aged 18-65, with CD4 cell counts 50-500 and who require endodontic treatment, will be selected. The teeth to be endodontically treated in these patients will be matched with similar teeth with similar diagnoses in 175 control patients who are presumably not HIV positive. Pretreatment blood samples will be analyzed for CD4 and CD8 cell counts, white blood cell count with differential, p24 antigen level, beta-2 microglobulin level, and erythrocyte sedimentation rate. These samples will be taken at the beginning of the study and at its completion in order to measure fluctuations during the course of the study. Posttreatment analysis will include clinical assessment for resolution of endodontic infection and subjective assessment for resolution of symptoms. Patients will be clinically examined at 3,6,12,18 and 24 months to diagnose successful or failed treatments. Logistic regression analysis will correlate the serological parameters with successful or failed treatments.